For mobile terminals such as mobile phones, various input apparatuses used by users to operate the terminals have been developed according to functions and usages of each of the terminals. In many cases, an input apparatus has mechanical keys or buttons arranged in advance on a surface of a body such that a user performs an input operation by directly pressing a finger or the like to the keys.
The mechanical keys (for example, a numerical keypad) of the input apparatus of the terminal are normally arranged in advance to suit a main usage of the terminal. Accordingly, it is generally not possible to change a physical arrangement of keys, once defined, later.
Recently, a variety of functions are incorporated in small mobile terminals. For example, the mobile phones have a digital camera function and a music player function. There are mobile terminals such as a mobile phone having numerous supplementary functions incorporated therein in addition to a function for a main usage of the terminal, and PDA (Personal Digital Assistant: mobile information terminal) having, as a single terminal, a plurality of main usages such as schedule management, an address book and the like. If such terminals have keys fixedly arranged, it may inconvenience the user significantly in using particular functions.
In order to resolve such inconvenience, there is disclosed an input apparatus having a touch panel designed such that a transparent input unit is arranged overlapping a front face of a liquid crystal display constituting a display unit (for example, see Patent Document 1). The input apparatus having such a touch panel generally displays graphical images of operation keys and buttons (hereinafter, referred to as “input objects”) on a display screen of the touch panel. When the user presses an input object displayed on the display screen, an input unit at a corresponding position on the touch panel receives an input.
A folding mobile phone described in the above Patent Document 1 can display input objects arbitrarily arranged on the display screen of the touch panel to receive input operations by the user, and thus key arrangements can be designed as desired. Accordingly, this mobile phone may provide an excellent operability, as capable of changing the arrangement of the input objects as desired to suit a function when each function of the terminal is switched. For example, when the user uses a digital camera function implemented in the mobile phone, this mobile phone may display input objects constituting an operation unit for a digital camera on the touch panel and receive operation inputs. On the other hand, when the user inputs characters in messages using the mobile phone, the mobile phone may display an input object constituting a keyboard like a personal computer (PC) on the touch panel and receive inputs. As stated above, this mobile phone having the touch panel can optimize a single input apparatus to suit each of a plurality of functions and receive operation inputs.
In addition, since the input apparatus having the touch panel receives an input in the form of a user's direct contact (touch) of a finger or the like to the input object displayed on the display unit, the user can operate it highly intuitively. That is, the user operates the input apparatus by directly touching the input object displayed on the screen with a finger or the like following a guide displayed on the screen of the touch panel. Accordingly, the user can operate the terminal extremely easily through intuitive operations following the guide displayed on the screen, which offers an effect to reduce incorrect operations as a result.
In recent years, the mobile terminal having the touch panel as stated above enables the user not only to make a normal telephone call and to perform operation inputs for creating a message but also to perform operation inputs to view (browse) contents delivered through the internet and websites. In addition, the input apparatuses having the touch panel are commonly used for not only the mobile terminals but also, for example, ATMs (Automatic Teller Machines) of a bank and the like and ticket vending machines at train stations. Moreover, in stores such as fast-food shops, terminal equipment with the input apparatus having the touch panel as above is used by a clerk to process orders from customers. When the touch panel is employed as the input apparatus, the mechanical buttons and keys such as the keyboard are not essential components any more. Accordingly, since only a small area is required to arrange mechanical buttons and the like on the terminal apparatus, it enables downsizing of overall terminal apparatus. Therefore, it offers a broader choice of installation sites of the terminal apparatus in stores and train stations.
In addition, the touch panel employed as the input apparatus eliminates the necessity of separately having a display unit for displaying various information and an input unit for receiving operation inputs by the user as individual function units like a general design of conventional apparatus, and enables to configure the information display unit and the input unit on the same screen. Accordingly, it is possible, for example, to display input object constituting keys of a keyboard on the touch panel to receive an input by the user while displaying a result of the input near the keyboard on the touch panel. Thereby, the user can perform an operation input and confirm the result of the input on the same screen.
As described above, the touch panel provides merits to enable to configure the input unit and the display unit on the same screen and also to enable intuitive operation inputs. For that reason, the number of terminal apparatuses having such input apparatus has been increased more and more.
However, the input apparatus with the touch panel has a specific problem because of its configuration to have the input unit and the display unit on the same screen and to receive the intuitive operation input. That is, although the touch panel can constitute the display unit arranging the input objects as desired, it is difficult for the user to determine a boundary between an input object and another area by a tactile sensation because a surface of the input unit is generally flat. In addition, since the user directly touches the input unit with a finger or a stylus in order to input to the touch panel, the input object is covered at the moment of the pressure input, preventing the user from visually confirming the input object to receive the operation input.
Accordingly, since the user cannot determine, with a feeling on the finger, whether the finger is touching an input object, there is always a possibility to press an unintended position. That is, there is a risk of pressing a position elsewhere than an intended input object by pressing a position slightly off from it or a risk of pressing another input object adjacent to the intended input object. When pressing an input object intended with a finger, a risk of unintended input becomes higher, as the input object is covered with the finger.
In addition, if the unintended input of the user is received by the input apparatus, an operation that the user does not intend may be started in response to the input. In such a case, the user must perform an additional operation to stop (cancel) the unintended operation. Moreover, if an important processing or operation being performed is stopped because of the unintended operation, it may cause an unrecoverable situation. Accordingly, it is desired to reduce a risk that such an unintended operation is started based on the unintended input by the user, as much as possible.
As a scheme capable of handling such a condition, there is suggested an input apparatus having a means to detect an input pressure to the touch panel and is configured to change a height of a surface of the touch panel in accordance with a position and the pressure of the input to the touch panel by the user (for example, see Patent Document 2).